The boat lifts currently designed for use with medium and larger size vessels exhibit a number of shortcomings. Normally, such lifts feature a respective motor, winder and independently driven cable system mounted to support posts or pilings on each longitudinal side of the boat. As a result, these mechanisms tend to be quite expensive and complicated. Installation is usually time consuming and labor intensive. Utilizing multiple motors is particularly costly and inefficient. Moreover, it is often quite difficult to accurately synchronize the operation of the motors. The respective sides of the lift platform which supports the vessel are apt to be raised or lowered at different rates. The platform is thereby likely to tilt during operation.
At least one known four piling boat lift has eliminated independently operated cables and associated cable beams from respective longitudinal sides of the lift. Instead, that device employs a pair of motors and corresponding pulley assemblies mounted at the front and back ends of the boat lift. This apparatus continues to require a pair of motors, which are quite costly and inefficient. It also exhibits synchronization problems because of the use of multiple independent motors.
Most conventional multiple cable/multiple piling boat lifts experience problems associated with speed reduction and cable wear. The output of each motor must be reduced to provide an appropriate speed and torque for raising and lowering the lift. Today, this almost always necessitates the use of a fairly complex reduction system. Standard cable winders or drums also tend to cause difficulties. Most known winders have a relatively small diameter, which tends to over-stress the cable as it is being wound onto or off of the winder. This can shorten the life of the cables, thereby requiring the lift owner to change cables more often. Such repairs are costly and render the lift inoperable while they are being performed.